The load is the value at a given moment of the electrical power supplied or absorbed at any point of a system as determined by an instantaneous measurement or by the integration of power during a given period of time. Load can refer to a consumer, an appliance, a group of consumers or appliances or a network.
Load is the power consumed by the network including (+) the transmission losses but excluding (-) the consumption for pumped storage.
For the power balance the load of each country, also called reference load, is represented at 11:00 a.m. CET (Central European Time) on the third Wednesday of each month without regard to the export power.
Concerning the calculation method for the 24 load values, the countries use the average values of the 10, 15 or 60 minutes load preceding the hour. UCTE uses CET (Central European Time) for collecting this data.

3.2 Rated capacity

highest permanent capacity - without time limit, without influencing the life time (operating time) and safety - of an electrical installation for which it is designed or after which it is "named".

3.3 Maximum electrical capacity (MW)

The maximum electrical capacity is the maximum power, which could be produced, transmitted or distributed continuously throughout a prolonged period of operation. All the equipment is assumed to be fully operational. It is the highest permanent power of a power station to be produced under average conditions for cooling water, fuel etc and is limited by the weakest component. Components which are temporarily out of service, e.g. for repair or overhaul, do not decrease the maximum electrical capacity.
This value remains constant for a given installation unless, following permanent modification, the management of the undertaking decides to amend the original value.
Maximum capacity is defined separately in this document :

Thermal power station unit
Co-generation power station
Interconnection

The maximum electrical capacity of a group of units or power stations is the arithmetic sum of the individual maximum electrical capacities. It therefore takes no account of possible restrictions, permanent or temporary.

3.4 Maximum electrical capacity of a hydro-electric head installation (MW)

The maximum electrical capacity of a hydro-electric head installation is the maximum capacity, assumed to be solely active power, that could be produced continuously throughout a long period of operation (generally not less than 4 hours) but compatible with its normal operating regime, with all plant running and with flow and head height at their optimum values.

The reference operating conditions are:

The head installation has available all its plants, all of which is in full working order, but after allowing for wear of a permanent nature. It is able to operate to accepted standards at its maximum, not necessarily optimum, active power rating compatible with its specified period of operation.
the installation operates under optimum conditions of flow and head height corresponding to the period of operation and compatible with security.
full account is taken of all plant limitations such as size of intake works, size of sluice, size of pressure conduits, size of discharge works, etc
production is not limited by any permanent or temporary restrictions on the network or by absence of demand.

3.5 Maximum electrical capacity of a unit or thermal power station (MW) (or reference power)

The maximum electrical capacity of a unit or a thermal power station is the maximum capacity, assumed to be solely active power, that could be produced continuously throughout a prolonged period of operation. All the equipment is assumed to be fully operational and with adequate fuel stocks of normal quality.
This capacity must be related to reference climatic conditions representative of the annual mean (or typical) ambient conditions for the power station.
The maximum electrical capacity excludes the capacity of power stations or units which are placed in reserve for longer than one year.

3.6 Maximum electrical capacity of a windpower installation (MW)

The maximum electrical capacity of a windpower installation is the maximum capacity, assumed to be solely active power, that could be produced continuously throughout a longer period of operation (generally not less than 4 hours) but compatible with its normal operating regime, with all plant running and with wind at its optimum value.

3.7 Physical load flow between neighbour countries (MW)

The physical load flow between neighbour countries represents the balance of the physical load flows, measured at 3 and 11 a.m. (Central European Time) at the cross-frontier substations of transmission lines (> 110 kV). In general, in agreement between the partners, a unique metering point is used.

3.8 Power produced in parallel operation (MW)

The power produced in parallel operation is the sum of the net electrical power produced in power stations participating in synchronous operation. It takes into account the spinning reserve, but excludes units injecting into systems, which are coupled to the interconnected network only by an AC/DC-link, and those, which cannot be operated with 50 Hz.

3.9 Overhauls of thermal power stations (MW)

Every utility fixes a periodical program to execute the necessary overhauls in thermal power stations. As far as possible overhauls are carried out during the summer and transitional months, when the load is low due to the time of the year or, in some countries, additional capacity is available in run-of-river plants.
As the summer off-peak-season is not sufficient, overhaul work also has to be carried out during the winter. Therefore acorresponding reserve capacity has to be planned with respect to the problem of reserve assessment, which rises especially for the winter.

3.10 Reliable capacity (MW)

The reliable capacity is obtained from the national generating and purchased power capacity after deducting all reductions in capacity and reserve capacities as for the non-usable capacity, overhauls and outages as well as the reserve for system services. This capacity was firmly available to cover the load.

3.11 Surplus of available capacity (MW)

The surplus of available capacity is the reliable capacity less the load and margin. It is guaranteed to a large extent because, when it is determined in the power balance, all reductions in capacity and all possible load increases under extreme conditions within each country are already taken into account. The calculated surplus of available capacity is due to the geographical extension of the UCTE and the associated transmission constraints not fully usable et each point of the network of the interconnected system.
A surplus capacity from hydro power stations may be available only for some hours every day because of the limited reservoir capacity. A surplus of available capacity usable for a long period of time has its origin mostly in thermal power stations. This capacity is represented expressly.
The long-term planning reserve is not included in the cold reserve, and therefore appears as surplus of available capacity. The surplus of available capacity must therefore not be considered as excess capacity.

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